1. Field of the Invention
The invention relates to a crosslinkable halogen-free resin composition as well as a cross-linked insulated wire and a cable using the composition.
2. Description of the Related Art
Electric wires used in stock rolling, automobiles or electrical equipment etc. may need a high abrasion resistance, a low-temperature performance and flame retardancy etc. In order to have a high abrasion resistance, a resin composition is used for an insulation layer of wire which includes as a base a highly crystalline polymer such as high-density polyethylene (HDPE). In addition, a halogen-based flame retardant or a phosphorus-based flame retardant such as red phosphorus is used that allows flame retardancy even in small additive amount since the high-density polyethylene is low in filler acceptability.
However, since the halogen-based flame retardant may generate a halogen gas upon being heated, a problem may arise that they lack in concern for globally growing environmental issues. Alternatively, a problem may arise that the phosphorus-based flame retardant such as red phosphorus may generate phosphine upon being heated or may cause a groundwater contamination due to phosphoric acid generated upon being discarded.
In order to avoid the problems, flame-retardant resin compositions are proposed which include a high-density polyethylene as a base polymer and a metal hydroxide as a flame retardant (e.g., JP-A-2002-60557 and JP-A-2004-156026). JP-A-2002-60557 and JP-A-2004-156026 disclose the flame-retardant resin compositions in which the metal hydroxide is mixed with a polymer blend including the high-density polyethylene and an ethylene-acrylic ester-maleic anhydride terpolymer etc.